Here is my product: https://matchkraft.com/. It is a marketing toolkit. I think you need to ask for feedback, asking why users don't want to pay for a premium subscription. So far, you are getting new users that is a good sign you are going to the right direction. Maybe, who is your ideal customer or maybe your product is ok but need more visibility (maybe paying ads). Try to get active users. I really want to... Source: 12 months ago

Calling a 3rd party API: There is a complete ecosystem providing "google-sheets-as-DB". I personally tested and recommend https://sheetson.com/ but there are a lot more with free tiers https://sheetsu.com/ https://sheety.co/. Source: about 2 years ago

I'm learning how to design by copying other people's designs. So I'd browse Dribbble and adapt the designs I liked to my product, or I'd find a good landing page on sites like saaslandingpage.com or landingfolio.com and build out sections of the websites I liked. Source: over 1 year ago

See Landing Folio & One Page Love for inspiration if you want to find great designed websites :). Source: over 2 years ago